Nowadays, organic light emitting displays (OLED) have become one of the hotspots in the study field of flat panel displays. Compared with liquid crystal displays, OLED has the advantages of low power consumption, low production cost, self light emitting, wide viewing angle and fast response and so on. Currently, OLED has begun to replace the traditional liquid crystal displays (LCD) in the display areas such as mobile-phones, PDAs and digital cameras. Pixel driving circuit design is the core technical content of OLED displays and has important meaning for the study.
OLED is current-driven and needs a stable current to control light emission, which is different from the TFT (Thin Film Transistor)-LCD that uses a stable voltage to control brightness.
Due to process technology, device aging and other reasons, in the original 2T1C driving circuit (comprising two thin film transistors and one capacitor), the threshold voltages of driving TFTs at each pixel are not uniform, which causes changes in the current flowing through the OLED at each pixel so that the display brightness are not uniform, thus affecting the display effect of the entire image.
In the known technology, one pixel circuit generally corresponds to one pixel. Each pixel circuit comprises at least one data voltage line, one operating voltage line and a plurality of scanning signal lines, which causes the corresponding production process more complicated, and not conducive to reducing the pixel pitch.